I have a Sugar Sand Tango with a Mercury Sportjet 175XR2 engine in it. The engine in it is brand new, however, it doesn't seem to have the giddy-up that it should have. The engine runs beautifully, idles nice, etc. but doesn't seem to rev out completely. It struggles to plane out and RPM's seem to top out at about 3,800. At that point the engine doesn't break up or miss at all, it just acts like that's all she has got. It also seems to take quite a bit for it to plane out. I'm trying to figure out if its a carburetor issue, timing issue, or electronic issue (computer). I would think if its timing it would run rough. So I am leaning towards carburetor or electronic. One question that I have is... is the flywheel for a 6 cylinder outboard the same as a flywheel for the Sportjet engine. The reason I am asking this is that before I bought this new longblock I had purchased a remanufactured engine from an entity that later on I learned operated in a sketchy manner and would mix and match parts from outboard engines and jet engines to attempt to create remanufactured motors and sell them at a premium. I found this out after having repeated failures on the engine and eventually having a different engine builder look at it. At that point the second opinion person told me that the person who built the engine used an outboard block with outboard heads and stuffed a jet crank in it. Also there were 3 different piston sizes in this build. When I bought this new long block (not the one from the sketchy builder) I put the electronics and carburetors on it from the (questionable) remanufactured engine. Now that the new engine doesn't seem to want to perform properly I am wondering if the flywheel that I had was actually an outboard flywheel and may be different causing the performance issue with my new engine. Please let me know if you have any knowledge or insight on this.Thanks